Crosslinked Structure-Containing Polyolefin Porous Support, Crosslinked Structure-Containing Separator For Lithium Secondary Battery Including The Same, Method For Manufacturing The Same, And Lithium Secondary Battery Including The Separator

Patent metadata

Field	Value
Publication number	US-2024222710-A1
Application number	US-202218289182-A
Country	US
Kind code	A1
Filing date	May 9, 2022
Priority date	May 7, 2021
Publication date	Jul 4, 2024
Grant date	—

Abstract

The present disclosure relates to a crosslinked structure-containing polyolefin porous support which includes a crosslinked structure including polymer chains interconnected directly with one another, has a shutdown temperature of 145° C. or less, causes no rupture after being exposed at 180° C. for 1 minute, and shows a ratio of the puncture strength after being exposed at 180° C. for 1 minute based on the puncture strength at 25° C. of 50-100%. The present disclosure also relates to a crosslinked structure-containing separator for a lithium secondary battery including the crosslinked structure-containing polyolefin porous support, a method for manufacturing the same, and a lithium secondary battery including the same.

First claim

1 . A crosslinked structure-containing polyolefin porous support comprising a crosslinked structure having polymer chains interconnected directly with one another, wherein the crosslinked structure-containing polyolefin porous support has a shutdown temperature of 145° C. or less, does not rupture after being exposed at 180° C. for 1 minute, and has a ratio of a puncture strength after being exposed at 180° C. for 1 minute based on the puncture strength at 25° C. of 50-100%.

2 . The crosslinked structure-containing polyolefin porous support according to claim 1 , which has the puncture strength of 50 gf or more after being exposed at 180° C. for 1 minute.

3 . The crosslinked structure-containing polyolefin porous support according to claim 1 , which has a tensile strength of 500 kgf/cm 2 or more in each of a machine direction and a transverse direction, after being exposed at 180° C. for 1 minute.

4 . The crosslinked structure-containing polyolefin porous support according to claim 1 , which has a crosslinking degree of 10-45%.

5 . A crosslinked structure-containing separator for a lithium secondary battery comprising the crosslinked structure-containing polyolefin support as defined in claim 1 .

6 . The crosslinked structure-containing separator according to claim 5 , further comprising an inorganic composite porous layer disposed on at least one surface of the crosslinked structure-containing polyolefin porous support, wherein the inorganic composite porous layer comprises an inorganic filler and a binder polymer.

7 . The crosslinked structure-containing separator according to claim 5 , further comprising
an inorganic composite porous layer disposed on at least one surface of the crosslinked structure-containing polyolefin porous support, and a porous adhesive layer disposed on the inorganic composite porous layer, wherein the inorganic composite porous layer comprises an inorganic filler and a first binder polymer; and and the porous adhesive layer comprises a second binder polymer.

8 . The crosslinked structure-containing separator according to claim 5 , which has a meltdown temperature of 160° C. or higher.

9 . The crosslinked structure-containing separator according to claim 7 , wherein a weight ratio of the inorganic filler to the first binder polymer is from 95:5 to 99.9:0.1.

10 . The crosslinked structure-containing separator for a lithium secondary battery according to claim 7 , wherein the first binder polymer comprises an acrylic polymer, polyacrylic acid, styrene butadiene rubber, polyvinyl alcohol, or two or more of them.

11 . The crosslinked structure-containing separator for a lithium secondary battery according to claim 7 , wherein the second binder polymer comprises poly(vinylidene fluoride), poly(vinylidene fluoride-co-hexafluoropropylene), poly(vinylidene fluoride-co-trichloroethylene), poly(vinylidene fluoride-co-tetrafluoroethylene), poly(vinylidene fluoride-co-trifluoroethylene), poly(methyl methacrylate), poly(ethylhexyl acrylate), poly(butyl acrylate), poly(acrylonitrile), poly(vinyl pyrrolidone), poly(vinyl acetate), poly(ethylhexyl acrylate-co-methyl methacrylate), poly(ethylene-co-vinyl acetate), polyethylene oxide, poly(arylate), or two or more of them.

12 . A method for manufacturing a crosslinked structure-containing separator for a lithium secondary battery, comprising:
preparing a polyolefin porous support comprising a photoinitiator; and irradiating ultraviolet rays to the polyolefin porous support comprising a photoinitiator, wherein a content of the photoinitiator is 0.015-0.36 parts by weight based on 100 parts by weight of the polyolefin porous support.

13 . The method for manufacturing a crosslinked structure-containing separator for a lithium secondary battery according to claim 12 , wherein the preparing the polyolefin porous support comprises coating and drying a photo-crosslinking composition containing the photoinitiator and a solvent on an outer side of the polyolefin porous support.

14 . The method for manufacturing a crosslinked structure-containing separator according to claim 13 , wherein the photo-crosslinking composition is a slurry for forming an inorganic composite porous layer comprising an inorganic filler, a binder polymer, the photoinitiator and the solvent.

15 . The method for manufacturing a crosslinked structure-containing separator according to claim 13 , wherein the coating and drying the photo-crosslinking composition comprises:
coating a slurry comprising an inorganic filler, a first binder polymer and a dispersion medium on at least one surface of the polyolefin porous support, followed by drying, to form an inorganic composite porous layer; and applying a coating solution comprising a second binder polymer, the photoinitiator and the solvent to the top surface of the inorganic composite porous layer, followed by drying, to form a porous adhesive layer.

16 . The method for manufacturing a crosslinked structure-containing separator according to claim 12 , wherein the photoinitiator comprises a Type 2 photoinitiator.

17 . The method for manufacturing a crosslinked structure-containing separator according to claim 12 , wherein the photoinitiator comprises thioxanthone (TX), a thioxanthone derivative, benzophenone (BPO), a benzophenone derivative, or two or more of them.

18 . The method for manufacturing a crosslinked structure-containing separator according to claim 12 , wherein ultraviolet rays are irradiated at an irradiation light dose of 10-2000 mJ/cm 2 .

19 . A lithium secondary battery comprising a positive electrode, a negative electrode and a separator interposed between the positive electrode and the negative electrode, wherein the separator is the crosslinked structure-containing separator of claim 5 .

Assignees

• Lg Chemical Ltd

Inventors

• Han Sung-Jae
• Lee Joo-Sung
• Mun Sung Cik

Classifications

• H01M10/052 Primary

  Li-accumulators · CPC title

• H01M50/494

  Tensile strength · CPC title

• H01M50/446

  Composite material consisting of a mixture of organic and inorganic materials · CPC title

• H01M50/426

  Fluorocarbon polymers · CPC title

• H01M50/417 Primary

  Polyolefins · CPC title